Methylene Diphenyl Isocyanate (MDI) Fact Sheet

This fact sheet is part of a series of chemical fact sheets developed by TURI to help Massachusetts companies, community organizations and residents understand the chemical's use and health and environmental effects, as well as the availability of safer alternatives. Since Massachusetts companies report usage under the Toxics Use Reduction Act, readers will learn how the chemicals are being used and by which companies.

Methylene Diphenyl Isocyanate (MDI) is a poison when inhaled. At room temperature MDI is a solid, but it is sold and used in molten form. Workplaces are the primary source of exposure to MDI, which is an intermediary chemical in the manufacture of polyurethanes. In Massachusetts MDI use is on the rise due to a single facility, which used over 10 million pounds in 1997 to manufacture roofing insulation.

Learn more about Methylene diphenyl isocyanate health effects, use in Massachusetts, and alternatives here.